JPH04348000A - Voice processor - Google Patents

Abstract

PURPOSE:To easily process voices without the influence of a wind or the like with compact and simple construction by providing a control means controlling attenuation characteristic in a low-pass frequency attenuation means. CONSTITUTION:BPFs 13 to 16 extracts low-pass frequency band signal and an intermediate frequency band signal from a voice signal to be generated respectively by microphones 1 and 2. A comparator circuit 25 compares the level of the low-pass detection signal to be supplied from detection circuits 21 and 22, and outputs the low-pass detection signal with higher level. A comparison circuit 26 compares the level of the intermediate detection signal to be supplied from detection circuits 23 and 24, and outputs the intermediate detection signal with higher level. A comparison circuit 27 outputs a comparison signal lowering the gain of the low-pass frequency band in variable filters 3 and 4 when the level of the low-pass detection signal to be outputted from the comparison circuit 25 is higher than that of the intermediate detection signal to be outputted from the comparison circuit 26 to be supplied to a time constant circuit 9.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an audio processing device for processing audio.

0002

[Background Art] Conventionally, audio processing devices have been used to form audio signals by converting audio into electrical signals using a microphone or the like, and record the formed audio signals on a recording medium using a tape recorder or the like. There is a device.

In the above-mentioned audio recording device, the frequency characteristics of the audio signal amplification circuit that amplifies the audio signal generated by the microphone are often almost constant, and in this case, when the microphone is hit by wind, recording Wind noise mixes into the audio you are trying to hear, degrading the audio signal, so the microphone was equipped with a windscreen to prevent the effects of the wind.

In addition, since the noise generated by the wind noise described above is a low-frequency signal in terms of frequency, in recent years, audio signal amplification circuits have been equipped with frequency characteristics so that the low frequency components can be removed from the audio signal. A changeover switch is provided, and an operator operates the changeover switch when there is wind to operate the audio signal amplification circuit to remove low frequency components of the audio signal, thereby preventing the influence of the wind.

[0005]

However, in the case of the above-mentioned conventional apparatus, there is a problem in that the apparatus becomes large in size when the wind screen is used to prevent the influence of wind.

[0006] Furthermore, when the operator arbitrarily operates a changeover switch to operate the audio signal amplification circuit to remove the low frequency components of the audio signal to prevent the influence of wind, the operator It is very difficult to judge the presence or absence of the switch and operate the changeover switch, and there is a possibility of erroneous operation.

That is, in order to judge the degree of influence of wind noise, the operator must constantly monitor the sound collected by the microphone, which is inconvenient for the operator.

Furthermore, when the switch is operated without monitoring the audio, the switch is not operated and the low frequency components of the audio signal are not removed even though the microphone is exposed to wind. Then, the level of the wind sound becomes higher than the level of the sound you are trying to record, and the AGC (Auto) in the audio signal amplification circuit.
Due to the function of the Gain Controller, the level of the overall sound collected by the microphone may drop due to the sound of the wind, or the level of the audio signal may be lowered by operating the changeover switch even though there is no wind hitting the microphone. If the low frequency components are left unremoved, the low frequency components of the sound collected by the microphone will always be removed, which will impair the sound quality of the sound being recorded.

The present invention solves the above-mentioned problems and provides an audio processing device that can easily process audio without being affected by noise such as wind with a simple configuration without increasing the size of the device. The purpose is to do.

0010

[Means for Solving the Problems] The audio signal processing device of the present invention is a device for processing audio, which inputs a first audio signal and processes a low frequency signal of the inputted first audio signal. a first low frequency attenuating means for attenuating and outputting; a second low frequency attenuating means for inputting a second audio signal, attenuating a low frequency signal of the inputted second audio signal, and outputting the low frequency signal; , depending on the level of the low frequency signal and the level of the middle frequency signal of the input first and second audio signals,
and a control means for controlling the attenuation characteristics of the first and second low frequency attenuation means, and further includes a control means for controlling the attenuation characteristics of the first and second low frequency attenuation means, and a control means for inputting the first audio signal and controlling the low frequency signal of the input first audio signal. a first low frequency attenuating means for attenuating and outputting; a second low frequency attenuating means for inputting a second audio signal, attenuating a low frequency signal of the inputted second audio signal, and outputting the low frequency signal; , the level of the low frequency signal of the input first and second audio signals and the intermediate frequency signal of the first and second audio signals output from the first and second low frequency attenuation means. and control means for controlling attenuation characteristics in the first and second low frequency attenuation means according to the level, and inputting the first audio signal,
a first low frequency attenuation means for attenuating and outputting a low frequency signal of an input first audio signal; and a low frequency signal of the input second audio signal for inputting a second audio signal; a second low frequency attenuating means for attenuating and outputting a second low frequency attenuating means; a first audio signal output from the first low frequency attenuating means; and a second audio signal output from the second low frequency attenuating means. a first audio signal output from the first low frequency attenuation means and a second audio signal output from the second low frequency attenuation means; subtracting means for forming and outputting a difference signal; the level of the low frequency signal of the input first and second audio signals and the level of the mid frequency signal of the sum signal output from the adding means; and control means for controlling the attenuation characteristics of the first and second low frequency attenuation means according to the frequency of the input first audio signal. a first frequency characteristic variable means for varying the characteristic and outputting it; a second frequency characteristic variable means for inputting the second audio signal, varying the frequency characteristic of the inputted second audio signal, and outputting the same; control means for controlling the variable characteristics in the first and second frequency characteristic variable means according to the level of the low frequency component and the level of the middle frequency component of the input first and second audio signals; and a first audio signal inputting a first audio signal, varying the frequency characteristics of the input first audio signal, and outputting the first audio signal.
a frequency characteristic variable means, a second frequency characteristic variable means for inputting a second audio signal, varying the frequency characteristic of the inputted second audio signal, and outputting the frequency characteristic of the inputted second audio signal; The first and second and a control means for controlling the variable characteristic in the frequency characteristic variable means, and a first frequency characteristic for inputting the first audio signal, varying the frequency characteristic of the inputted first audio signal, and outputting the same. a variable means, a second frequency characteristic variable means for inputting a second audio signal, varying the frequency characteristic of the inputted second audio signal, and outputting the frequency characteristic of the input second audio signal; addition means for forming and outputting a sum signal of the first audio signal and the second audio signal output from the second frequency characteristic variable means; and the first audio signal output from the first frequency characteristic variable means. subtraction means for forming and outputting a difference signal between the signal and the second audio signal outputted from the second frequency characteristic variable means; and control means for controlling the variable characteristics in the first and second frequency characteristic variable means according to the level and the level of the mid-range frequency component of the sum signal outputted by the addition means, further comprising: a first frequency characteristic variable means for inputting a first audio signal, varying the frequency characteristic of the input first audio signal, and outputting the first audio signal;
a second frequency characteristic variable means for varying the frequency characteristic of the input second audio signal and outputting the same; and control means for controlling variable characteristics in the second frequency characteristic variable means.

[0011]

[Operation] According to the above configuration, it becomes possible to easily process audio without increasing the size of the device and with a simple configuration without being affected by noise in the low frequency band such as wind. .

0012

EXAMPLES The present invention will be explained below using examples of the present invention.

FIG. 1 is a diagram showing a schematic configuration of an audio recording apparatus as a first embodiment of the present invention.

In FIG. 1, reference numerals 1 and 2 are microphones for converting audio into electrical signals; 1 is a microphone for the left side;
2 is a microphone for the right side. 3 and 4 are variable filters for changing the frequency characteristics of the audio signals generated by the microphones 1 and 2, respectively; 28 is a voltage control amplifier 5 and 6; detection circuits 7 and 8; a time constant circuit 10; and a comparison circuit. 11, which amplifies the audio signal output from the variable filters 3 and 4 according to its level.
C (Auto Gain Control) circuit,
Reference numeral 12 records the audio signal amplified by the AGC circuit 28 on a recording medium such as a magnetic tape; 13 and 14 separate low frequency components of the audio signals generated by the microphones 1 and 2, respectively. Band pass filters (BPF) 17 and 18 are amplifiers for amplifying the signals separated by the BPFs 13 and 14, and 21 and 22 are the low frequency component signals of the audio signals amplified by the amplifiers 17 and 18. detection circuits 15 and 16 are BPs for separating the middle frequency components of the audio signals generated from the microphones 1 and 2, respectively.
F, 19 and 20 are amplifiers that amplify the signals separated by the BPFs 15 and 16; 23 and 24 are the amplifiers 19;
, 20 is a detection circuit that detects the signal of the mid-range frequency component of the amplified audio signal and outputs the mid-range detection signal; 25 is the low-frequency detection signal output from the detection circuit 21 and the output from the detection circuit 22; A comparison circuit 26 compares the level of the low-frequency detection signal with the low-frequency detection signal outputted from the detection circuit 24 and outputs the low-frequency detection signal with the larger level. A comparator circuit 27 compares the level of a mid-range detection signal with a mid-range detection signal having a higher level, and outputs the mid-range detection signal having a higher level. A comparison circuit 9 outputs a comparison signal obtained by comparing the mid-range detection signal with the mid-range detection signal and subtracting the level of the mid-range detection signal from the level of the low-range detection signal; The controlled variable filters 3, 4
This is a time constant circuit for setting the attack recovery time to prevent changes in frequency characteristics from becoming audible.

In FIG. 1, sounds collected by microphones 1 and 2 are converted into electrical signals (that is, audio signals), and are passed through variable filters 2 and 4 and BPFs 13 to 16.
supplied to

FIGS. 2 and 3 show the microphones 1 and 2.
Figure 2 shows the frequency characteristics of the signal output from the
A in FIG. 3 indicates the frequency characteristic of the voice to be recorded, and W indicates the frequency characteristic of wind noise.

As shown in FIGS. 2 and 3, the frequency characteristics of voice are distributed around 1 kHz, except in special cases, and the frequency characteristics of wind noise are distributed in a low frequency band of 200 Hz or less. .

If there is not much difference between the wind noise level and the voice level as shown in FIG. 3, the wind noise will not be perceptibly noticeable compared to the voice, but as shown in FIG. If the sound level is low compared to the wind noise level, the wind noise will be audibly noticeable compared to the sound, and usually the wind noise will be more noticeable than the sound as shown in Figure 1 before being recorded on a recording medium such as magnetic tape.
Since the level of the audio signal is controlled by the AGC circuit 28 as shown in 28 so that it does not exceed a predetermined level, when the level of wind noise is high, the level of wind noise is limited, so the level of the audio is relatively low. As a result, wind noise becomes more and more noticeable.

Furthermore, in order to eliminate the influence of wind noise, conventional audio amplification circuits of tape recorders and the like often attenuate the signal component of wind noise by attenuating audio signals of 100 Hz or less. Alternatively, as shown in Figure 3, it is also distributed at high frequencies, so even if an audio signal of 100 Hz or less is attenuated, the high frequency components of wind noise in the frequency band of 50 to 200 Hz, for example, remain unattenuated. This will degrade the sound quality of the audio you are trying to record.

Therefore, in this embodiment, the BPFs 13 and 14 in FIG. 1 having a low-pass frequency band indicated by L in FIG. 4 and the BPF 14 in FIG. 1 having a middle-pass frequency band indicated by M in FIG.
15 and 16 extract a low frequency band signal and a medium frequency band signal from the audio signals generated from the microphones 1 and 2, respectively, and extract the signals from the audio signals generated from the two microphones 1 and 2. A low frequency detection signal with a higher detection level among the extracted low frequency band signals, and 2
Out of the mid-frequency band signals extracted from the audio signals generated by the two microphones 1 and 2, the signal generated by the microphones 1 and 2 is determined according to the difference between the mid-range detection signal of the one with a higher detection level. For example, the signal passing characteristics of the variable filters 3 and 4 to which the audio signal is supplied can be changed by changing the amount of attenuation in the low frequency range as shown in Fig. 5, or by changing the cutoff frequency in the low range as shown in Fig. 6. It is configured to remove the influence of wind noise by

The above processing operation will be explained in detail below.

Audio signals output from microphones 1 and 2 in FIG. 1 are supplied to BPFs 13-16.

The BPFs 13 and 14 in FIG. 1 extract the low frequency band signals shown by L in FIG. 4 from the audio signals supplied from the microphones 1 and 2, and the extracted signals are sent to the next stage. The signals are amplified by amplifiers 17 and 18 and supplied to detection circuits 21 and 22.

In the detection circuits 21 and 22, the BPF 13,
By detecting the low frequency band signal extracted by 14, low frequency detection signals are output from the detection circuits 21 and 22 and supplied to the comparison circuit 25.

The comparison circuit 25 compares the levels of the low-frequency detection signals supplied from the detection circuits 21 and 22, and supplies the low-frequency detection signal with the higher level to the comparison circuit 27 at the next stage.

Furthermore, the BPFs 15 and 16 in FIG. 1 extract signals in the mid-frequency band indicated by M in FIG. 4 from the audio signals supplied from the microphones 1 and 2, and the extracted signals are as follows. It is amplified by amplifiers 19 and 20 in the stage and supplied to detection circuits 23 and 24.

In the detection circuits 23 and 24, the BPF 15,
By detecting the signal in the mid-frequency band extracted by the detector 16, the detection circuits 23 and 24 output a mid-range detection signal, which is supplied to the comparison circuit 26.

The comparison circuit 26 compares the levels of the mid-range detection signals supplied from the detection circuits 23 and 24, and supplies the mid-range detection signal with the higher level to the comparison circuit 27 at the next stage.

The comparison circuit 27 compares the level of the low-frequency detection signal output from the comparison circuit 25 and the level of the mid-range detection signal output from the comparison circuit 26, and performs low-frequency detection according to the level difference. The higher the level of the signal is than the level of the mid-range detection signal, the more the variable filter 3
, 4 is output, and is supplied to the time constant circuit 9.

The time constant circuit 9 integrates the comparison signal output from the comparison circuit 27 using a capacitor or the like, and when the level of the integrated signal exceeds a predetermined threshold, the variable filter is activated in accordance with the level of the integrated signal. The pass characteristics of the variable filters 3 and 4 are continuously changed in the direction of attenuating the low frequency components, and the capacitor is discharged, and even when the capacitor is discharged, the pass characteristics of the variable filters 3 and 4 are changed to attenuate the low frequency components. By continuously changing the frequency characteristics in the attenuating direction, the variable filters 3 and 4 can attenuate the wind noise signal component (W' in the figure) mixed in the audio signal as shown in FIG. This is done so that the changes in the sound do not become difficult to hear.

The audio signal whose wind noise signal component has been attenuated by the variable filters 3 and 4 is sent to the AGC circuit 28.
After the level is limited so that it does not exceed a predetermined level, the recording section 12 records it on a recording medium such as a magnetic tape.

By the way, the AGC circuit 28, as shown in FIG. The supplied audio signals are amplified by voltage-controlled amplifiers 5 and 6 and supplied to the recording section 12, and the audio signals output from the voltage-controlled amplifiers 5 and 6 are supplied to detection circuits 7 and 8, The detection signal formed by detection in circuits 7 and 8 is sent to comparator circuit 1.
1.

The comparison circuit 11 compares the levels of the detection signals supplied from the detection circuits 7 and 8, and uses the detection signal with a higher level as a control signal for the voltage control amplifiers 5 and 6 via the time constant circuit 10. is supplied to the voltage control amplifiers 5 and 6.

When the level of the supplied detection signal exceeds a predetermined level, the voltage control amplifiers 5 and 6 reduce the gain for the input audio signal according to the level. 6 outputs an audio signal whose level is limited so as not to exceed a predetermined level.
It will be supplied to the recording section 12.

The time constant circuit 10 controls the detection signal outputted from the comparator circuit 11 at a predetermined time so that the level of the audio signal in the voltage control amplifiers 5 and 6 is controlled so that it does not become difficult to hear. A constant is supplied to the voltage control amplifiers 5 and 6.

As described above, in this embodiment, depending on the difference between the level of the low frequency component and the level of the middle frequency component of the audio signal output from the microphone, the low frequency component of the audio signal is By configuring the variable filter to change the frequency characteristics of the variable filter that attenuates, when the level of the mid-range frequency component is high, the low-range frequency component is not attenuated, but when the level of the mid-range frequency component is low, it is It is possible to attenuate low frequency components and make the wind noise signal component mixed in the audio signal audibly inconspicuous. Furthermore, as shown in Figure 1, AGC is applied before recording to a recording medium.
Even if the noise level is increased, it is possible to prevent the level of the audio signal to be recorded from being attenuated due to the influence of the wind noise signal component.

Furthermore, in this embodiment, the microphone 1,
Since the low frequency pass characteristics of the variable filters 3 and 4 for controlling the level of the low frequency components of the audio signals generated by the audio signals 2 and 2 are both controlled by the comparison signal generated by the comparison circuit 27, stereo It becomes possible to maintain a balance in frequency characteristics for the audio signals generated from the microphones 1 and 2 used as microphones.

FIG. 8 is a diagram showing a schematic configuration of an audio recording device according to a second embodiment of the present invention. Components similar to those of the first embodiment shown in FIG. 1 are designated by the same reference numerals. , and detailed explanation will be omitted.

In the embodiment shown in FIG. 1, a low frequency component signal and a middle frequency component signal are extracted from the audio signals generated by the microphones 1 and 2 and before being supplied to the variable filters 3 and 4. However, in such a configuration, it is necessary to increase the amplification factor in the amplifiers 19 and 20 that amplify the extracted mid-range frequency component signal, and to achieve this, many parts are required. This increases the cost.

Therefore, as shown in FIG. 8, the medium frequency component signal in the audio signal whose frequency characteristics are not changed by the variable filters 3 and 4 is processed in the AGC circuit 28 so that it does not exceed a predetermined level. B from the amplified audio signal
By configuring the output to be extracted by the BPFs 15 and 16, the amplifiers 19' and 19' are connected to the next stage of the BPFs 15 and 16.
Since the amplifier 20' does not need to have a high amplification factor and only needs a lower amplification factor than the amplifiers 19 and 20 shown in FIG. 1, it is possible to obtain the same effect as the first embodiment shown in FIG. The number of parts can be reduced, the configuration can be simplified, and costs can be reduced.

In addition, in the second embodiment shown in FIG. Although the configuration is such that they are extracted separately, as in the third embodiment of the present invention as shown in FIG. 9, the left audio signal generated from microphone 1 and the right audio signal generated from microphone 2 are The audio signal is converted into a sum signal formed by adding both signals by an adder 29 and a difference signal formed by subtracting by a subtracter 30, and the resultant signal is recorded on a recording medium. In the audio signal recording device, a mid-range frequency component signal is extracted from the sum signal output from the adder 29 by the BPF 15, amplified by the amplifier 19, detected by the detection circuit 23, and the detected signals are compared. By configuring the circuit 27 so that it is supplied to the circuit 27, the second
It is possible to obtain the same effect as in the embodiment B of FIG.
PF16, amplifier 20', detection circuit 24, comparison circuit 26
Since this can be omitted, the configuration can be simplified and costs can be reduced.

In each of the first to third embodiments described above, the low frequency component signal and the mid frequency component signal of the audio signal output from the microphone are extracted, and both signals are extracted. It is configured to control the characteristics of a variable filter that changes the low frequency characteristics of the audio signal according to the difference in detection level, but the detection level between the low frequency component signal and the mid-high frequency component signal The characteristics of the variable filter may be controlled in accordance with the difference between the two or the comparison results of the detection levels of the low frequency component signal, the middle frequency component signal, and the high frequency component signal. .

In the first to third embodiments described above, the audio signal is amplified by the AGC circuit before being supplied to the recording section, but it may also be a simple amplifier. The comparison circuits 25 and 26 compare the supplied detection signals and output the detection signal with a higher level, but the supplied detection signals may be added together and output.

Furthermore, in the first to third embodiments described above, the configuration is such that a low frequency component signal is extracted from the audio signal generated by the microphone and before being supplied to the variable filter. However, the filter extracts a low frequency component signal from the audio signal passed through the variable filter, and uses the extracted low frequency component signal to control the gain of the variable filter for the low frequency component. Eid back loop control may also be performed and similar effects can be obtained.

FIG. 10 is a diagram showing a schematic configuration of an audio recording apparatus as a fourth embodiment of the present invention.

In FIG. 10, reference numerals 31 and 32 are variable equalizers for changing the frequency characteristics of the audio signals generated by the microphones 1 and 2, respectively, and the other configurations are the same as those in the first embodiment shown in FIG. Since the configuration is the same as that of the example, the same reference numerals are given, and detailed explanation will be omitted.

In this embodiment, the BPFs 13 and 14 in FIG. 10 having a low-pass frequency band indicated by L in FIG.
The BPF 15 in FIG. 10 has a mid-pass frequency band shown as
, 16, a low frequency band signal and a medium frequency band signal are extracted from the audio signals generated from the microphones 1 and 2, respectively, and extracted from the audio signals generated from the two microphones 1 and 2. The detection level of the low frequency band signal extracted from the low frequency band signal with a higher detection level and the mid frequency band signal extracted from the audio signal generated from the two microphones 1 and 2. The frequency characteristics of the variable equalizers 31 and 32 to which the audio signals generated by the microphones 1 and 2 are supplied are determined depending on the difference from the larger mid-range detection signal, for example, as shown in FIG. It is configured to remove the influence of wind noise by changing the level of the component or by changing the low cutoff frequency as shown in FIG.

The above processing operation will be explained in detail below.

Audio signals output from microphones 1 and 2 in FIG. 10 are supplied to BPFs 13-16.

The BPFs 13 and 14 in FIG. 10 extract signals in the low frequency band indicated by L in FIG. 4 from the audio signals supplied from the microphones 1 and 2, and the extracted signals are transmitted to the next stage. The signals are amplified by amplifiers 17 and 18 and supplied to detection circuits 21 and 22.

In the detection circuits 21 and 22, the BPF 13,
By detecting the low frequency band signal extracted by 14, low frequency detection signals are output from the detection circuits 21 and 22 and supplied to the comparison circuit 25.

The comparison circuit 25 compares the levels of the low-frequency detection signals supplied from the detection circuits 21 and 22, and supplies the low-frequency detection signal with the higher level to the comparison circuit 27 at the next stage.

Furthermore, the BPFs 15 and 16 in FIG. 10 extract the signals in the mid-frequency band indicated by M in FIG. 4 from the audio signals supplied from the microphones 1 and 2, and the extracted signals are as follows. It is amplified by amplifiers 19 and 20 in the stage and supplied to detection circuits 23 and 24.

In the detection circuits 23 and 24, the BPF 15,
By detecting the signal in the mid-frequency band extracted by the detector 16, the detection circuits 23 and 24 output a mid-range detection signal, which is supplied to the comparison circuit 26.

The comparison circuit 26 compares the levels of the mid-range detection signals supplied from the detection circuits 23 and 24, and supplies the mid-range detection signal with the higher level to the comparison circuit 27 at the next stage.

The comparison circuit 27 compares the level of the low-frequency detection signal output from the comparison circuit 25 and the level of the mid-range detection signal output from the comparison circuit 26, and performs low-frequency detection according to the level difference. The greater the level of the signal is than the level of the mid-range detection signal, the more the time constant circuit 9 supply to.

In the time constant circuit 9, the comparison signal output from the comparison circuit 27 is integrated by a capacitor or the like, and when the level of the integrated signal exceeds a predetermined threshold, the variable equalizer is adjusted according to the level of the integrated signal. Continuously changing the frequency characteristics of 31 and 32 in the direction of decreasing the level of the low frequency component, and discharging the capacitor,
Even when the capacitor is discharged, the variable equalizers 31, 3
By continuously changing the frequency characteristics of 2 in the direction of decreasing the level of low frequency components, the variable equalizers 31 and 32 reduce the wind noise signal component mixed into the audio signal as shown in FIG. This is done so that changes in frequency characteristics for attenuating W') do not become audible.

The audio signal whose wind noise signal component has been attenuated in the variable equalizers 31 and 32 is level-limited in the AGC circuit 28 so as not to exceed a predetermined level, and then recorded in the recording section 12 on a magnetic tape or the like. recorded on the medium.

As described above, in this embodiment, depending on the difference between the level of the low frequency component and the level of the middle frequency component of the audio signal output from the microphone, the low frequency component of the audio signal is By configuring the variable equalizer to change the frequency characteristics of the variable equalizer that reduces the level of If it is small, the level of the low frequency component can be reduced, making the wind noise signal component mixed in the audio signal audibly less noticeable, and furthermore, as shown in FIG. Even if AGC is applied before recording, it is possible to prevent the level of the audio signal to be recorded from being attenuated due to the influence of the wind noise signal component.

Furthermore, in this embodiment, the microphone 1,
Since the frequency characteristics of the variable equalizers 31 and 32 for controlling the level of the low-frequency components of the audio signals respectively generated by the microphones 2 and 2 are controlled by the comparison signal generated by the comparison circuit 27, it is used as a stereo microphone. For the audio signals generated from microphones 1 and 2,
It becomes possible to maintain a balance in frequency characteristics.

FIG. 13 is a diagram showing a schematic configuration of an audio recording device as a fifth embodiment of the present invention, and is similar to FIG.
Components similar to those in the fourth embodiment shown in FIG.

In the embodiment shown in FIG.
In this configuration, an amplifier is required to amplify the extracted mid-frequency component signal. It is necessary to increase the amplification factors at 19 and 20, and realizing this requires many parts, which increases the cost.

Therefore, as shown in FIG. 13, the medium frequency component signal in the audio signal whose frequency characteristics are not changed by the variable equalizers 31 and 32 is sent to the AGC circuit 28.
By configuring the BPFs 15 and 16 to extract the audio signal from the amplified audio signal so as not to exceed a predetermined level, the amplifiers 19' and 20' connected to the next stage of the BPFs 15 and 16 increase the amplification factor. Figure 10
Since the amplification factor is lower than that of the amplifiers 19 and 20 shown in FIG. 10, the same effect as the fourth embodiment shown in FIG. 10 can be obtained, and the number of parts can be reduced and the configuration can be simplified. , it is possible to reduce costs.

In addition, in the fifth embodiment shown in FIG. Although the configuration is such that they are extracted separately, as in the sixth embodiment of the present invention as shown in FIG. 14, the left audio signal generated from microphone 1 and the right audio signal generated from microphone 2 are The audio signal is converted into a sum signal formed by adding both signals by an adder 29 and a difference signal formed by subtracting by a subtracter 30, and the resultant signal is recorded on a recording medium. In the audio signal recording device, the adder 2
The BPF 15 extracts a mid-range frequency component signal from the sum signal output from the sum signal output from the sum signal output from the comparator circuit 2.
7, the same effect as the fifth embodiment shown in FIG. 13 can be obtained, and the BPF 16, amplifier 20', detection circuit 24, and comparison circuit 26 in FIG. 13 are omitted. This makes it possible to simplify the configuration and reduce costs.

In the fourth to sixth embodiments described above, the low frequency component signal and the mid frequency component signal of the audio signal output from the microphone are extracted, and both signals are extracted. The variable equalizer is configured to control the frequency characteristics of a variable equalizer that changes the low frequency characteristics of the audio signal according to the difference in detection level, but it is difficult to detect the low frequency component signal and the mid-high frequency component signal. The variable equalizer is configured to control the frequency characteristics according to the difference in level or the comparison result of the detection level of each of the low frequency component signal, the middle frequency component signal, and the high frequency component signal. Also good.

In the fourth to sixth embodiments described above, the audio signal is amplified by the AGC circuit before being supplied to the recording section, but it may also be a simple amplifier. The comparison circuits 25 and 26 compare the supplied detection signals and output the detection signal with a higher level, but the supplied detection signals may be added together and output.

Furthermore, the fourth to sixth embodiments described above are configured to extract low frequency component signals from the audio signal generated by the microphone and before being supplied to the variable equalizer. However, the filter extracts a low frequency component signal from the audio signal passed through the variable equalizer, and uses the extracted low frequency component signal to control the level of the low frequency component of the variable equalizer. Eid back loop control may also be performed and similar effects can be obtained.

[0068]

[Effects of the Invention] As explained above, according to the present invention, the device has a simple configuration without increasing the size of the device, and the audio can be easily processed without being affected by noise such as wind. We will be able to provide processing equipment.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a schematic configuration of an audio recording device as a first embodiment of the present invention.

FIG. 2 is a diagram showing frequency characteristics of a signal output from a microphone in the audio recording apparatus shown in FIG. 1;

3 is a diagram showing frequency characteristics of a signal output from a microphone in the audio recording apparatus shown in FIG. 1; FIG.

FIG. 4 is a diagram showing frequency characteristics of a bandpass filter in the audio recording device shown in FIG. 1;

FIG. 5 is a diagram showing frequency characteristics of a variable filter in the audio recording device shown in FIG. 1;

6 is a diagram showing another frequency characteristic of the variable filter in the audio recording device shown in FIG. 1. FIG.

7 is a diagram showing the frequency characteristics of a signal output from a variable filter in the audio recording apparatus shown in FIG. 1. FIG.

FIG. 8 is a diagram showing a schematic configuration of an audio recording device as a second embodiment of the present invention.

FIG. 9 is a diagram showing a schematic configuration of an audio recording device as a third embodiment of the present invention.

FIG. 10 is a diagram showing a schematic configuration of an audio recording device as a fourth embodiment of the present invention.

11 is a diagram showing frequency characteristics of a variable equalizer in the audio recording device shown in FIG. 10. FIG.

12 is a diagram showing another frequency characteristic of the variable equalizer in the audio recording device shown in FIG. 10. FIG.

FIG. 13 is a diagram showing a schematic configuration of an audio recording device as a fifth embodiment of the present invention.

FIG. 14 is a diagram showing a schematic configuration of an audio recording device as a sixth embodiment of the present invention.

[Explanation of symbols]

1 Microphone 2 Microphone 3. Variable filter 4 Variable filter 5 Voltage control amplifier 6 Voltage control amplifier 7 Detection circuit 8 Detection circuit 9 Time constant circuit 10 Time constant circuit 11 Comparison circuit 12 Recording Department 13 Bandpass filter 14 Bandpass filter 15 Bandpass filter 16 Bandpass filter 17 Amplifier 18 Amplifier 19 Amplifier 20 Amplifier 21 Detection circuit 22 Detection circuit 23 Detection circuit 24 Detection circuit 25 Comparison circuit 26 Comparison circuit 27 Comparison circuit 28 AGC circuit 29 Adder 30 Subtractor 31 Variable equalizer 32 Variable equalizer

Claims (7)

[Claims] 1. An apparatus for processing audio, comprising: a first low frequency attenuation means for inputting a first audio signal, attenuating a low frequency signal of the input first audio signal, and outputting the low frequency signal; , a second low frequency attenuation means for inputting a second audio signal, attenuating a low frequency signal of the input second audio signal, and outputting the low frequency signal; and the input first and second audio signals. and a control means for controlling attenuation characteristics in the first and second low frequency attenuation means according to the level of the low frequency signal and the level of the middle frequency signal. 2. An apparatus for processing audio, comprising first low frequency attenuating means for inputting a first audio signal, attenuating a low frequency signal of the input first audio signal, and outputting the low frequency signal. , a second low frequency attenuation means for inputting a second audio signal, attenuating a low frequency signal of the input second audio signal, and outputting the low frequency signal; and the input first and second audio signals. the first and second low frequency signals according to the levels of the low frequency signals of the first and second audio signals output from the first and second low frequency attenuation means. 1. A sound processing device comprising: control means for controlling attenuation characteristics in the range frequency attenuation means. 3. A device for processing audio, comprising first low frequency attenuating means for inputting a first audio signal, attenuating a low frequency signal of the input first audio signal, and outputting the low frequency signal. , a second low frequency attenuation means for inputting a second audio signal, attenuating a low frequency signal of the input second audio signal and outputting the low frequency signal, and a second low frequency attenuation means for attenuating and outputting a low frequency signal of the input second audio signal; addition means for forming and outputting a sum signal of the first audio signal and the second audio signal output from the second low frequency attenuation means; subtracting means for forming and outputting a difference signal between the first audio signal and the second audio signal output from the second low frequency attenuation means; control means for controlling attenuation characteristics in the first and second low frequency attenuation means according to the level of the mid range frequency signal and the level of the mid range frequency signal of the sum signal outputted from the addition means. An audio processing device characterized by: 4. An apparatus for processing audio, comprising a first frequency characteristic varying means for inputting a first audio signal, varying the frequency characteristic of the inputted first audio signal, and outputting the frequency characteristic; a second frequency characteristic variable means for inputting an audio signal, varying the frequency characteristic of the input second audio signal, and outputting the frequency characteristic of the input second audio signal; An audio processing device comprising: control means for controlling the variable characteristics of the first and second frequency characteristic variable means according to the level and the level of the mid-range frequency component. 5. An apparatus for processing audio, comprising a first frequency characteristic variable means for inputting a first audio signal, varying the frequency characteristic of the inputted first audio signal, and outputting the frequency characteristic; a second frequency characteristic variable means for inputting an audio signal, varying the frequency characteristic of the input second audio signal, and outputting the frequency characteristic of the input second audio signal; The variable characteristics in the first and second frequency characteristic variable means are adjusted according to the level and the level of the mid-range frequency component of the first and second audio signals output from the first and second frequency characteristic variable means. A voice processing device characterized by having a control means for controlling. 6. An apparatus for processing audio, comprising: a first frequency characteristic variable means for inputting a first audio signal, varying the frequency characteristic of the inputted first audio signal, and outputting the frequency characteristic; a second frequency characteristic variable means for inputting an audio signal, varying the frequency characteristic of the input second audio signal, and outputting the same; a first audio signal output from the first frequency characteristic varying means; addition means for forming and outputting a sum signal with a second audio signal output from the second frequency characteristic variable means; and a first audio signal output from the first frequency characteristic variable means and the second frequency. subtraction means for forming and outputting a difference signal with the second audio signal output from the characteristic variable means;
The first and second frequency characteristics are variable according to the levels of the low frequency components of the input first and second audio signals and the level of the mid frequency components of the sum signal output from the adding means. 1. A sound processing device comprising: control means for controlling variable characteristics in the means. 7. An apparatus for processing audio, comprising a first frequency characteristic variable means for inputting a first audio signal, varying the frequency characteristic of the inputted first audio signal, and outputting the frequency characteristic; a second frequency characteristic variable means for inputting an audio signal, varying the frequency characteristic of the input second audio signal, and outputting the frequency characteristic; and control means for controlling variable characteristics in the first and second frequency characteristic variable means accordingly.